The instant invention is connected with an industrial process for preparing N-(mercaptoacyl) amino acid derivatives from xcex1-substituted acrylic acids.
The invention relates more particularly to a novel process for synthesizing N-(mercaptoacyl) amino acid derivatives of general formula (I): 
wherein
R1 represents:
a phenyl group; or
a 3,4-methylenedioxyphenyl group
R2 represents a hydrogen atom or a lower alkyl group;
R3 represents a hydrogen atom, a lower alkyl group or a lower phenylalkylene group; and
R4 represents a linear or branched aliphatic acyl radical or an aromatic acyl radical.